The invention relates to a novel filament and configuration of such filament, more particularly to a composite high-nitrile filament. Filaments herein mean filaments composed of two or more polymers arranged in a sheath core type configuration wherein the sheath is composed of a polymer that is different than the polymer that makes up the core. In particular, one polymer comprises a solventless, waterless, melt-processable acrylonitrile olefinically unsaturated polymer and the other polymer comprises an organic polymer.
The unique composite high-nitrile filament provides improved dyeabiltiy; and improved resistance to abrasion, solvents, gas and ultraviolet light. The high-nitrile filaments are employed to form high-nitrile composite fibers which, in turn, can be used as knitted, woven or nonwoven objects.
Bicomponent acrylic fibers known in the art are exemplified by U.S. Pat. No. 3,547,763, U.S. Pat. No. 4,020,139, and Japanese patent application 6[1994]-189,463. U.S. Pat. No. 3,547,763 relates to bi-component acrylic fibers having a modified helical crimp. Each component is selected from a group consisting of (1) polyacrylonitrile and (2) copolymers of at least 88% acrylonitrile and 12% of copolymerizable monomers.
U.S. Pat. No. 4,020,139 relates to a process for melt spinning a plurality of eccentric sheath core filaments. The process selects filaments to be converged into a yarn so as to avoid contact between the thin sheath regions of the filament during conversion.
Japanese patent application 6[1994]-189,463 discloses anti-static acrylic fibers with a sheath core structure made by a solution solvent process. The sheath component consists of an acrylonitrile based copolymer, and the core component consists of an acrylonitrile based copolymer and a multi-functional polyether ester.
Difficulties in the development of composite high-nitrile filaments are due to the fact that polymers of different composition types are often incompatible with each other. The use of two different polymers, even with similar chemical characteristics, in a composite filament often results in the generation of internal stresses, thereby inducing the composite filament to split. Prior art composite acrylic filaments are limited because of poor fiber formation. Additionally, melt spinning composite filaments is problematic because many of the polymers have low resistance to thermal degradation.
It is advantageous to produce a high-nitrile composite fiber wherein one of the polymers employed as the sheath or the core component is a solventless, waterless melt-processable acrylonitrile olefinically unsaturated polymer. Furthermore, the high nitrile composite filaments of the instant invention have improved processability and, in particular, improved spinnabilty. These and other advantages will become apparent as the description of the invention proceeds.